CA1331781C - Lightening arrestor insulator and method of producing the same - Google Patents
Lightening arrestor insulator and method of producing the sameInfo
- Publication number
- CA1331781C CA1331781C CA000594425A CA594425A CA1331781C CA 1331781 C CA1331781 C CA 1331781C CA 000594425 A CA000594425 A CA 000594425A CA 594425 A CA594425 A CA 594425A CA 1331781 C CA1331781 C CA 1331781C
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- Canada
- Prior art keywords
- insulator
- arrestor
- lightening
- zno element
- electrodes
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
- H01C7/12—Overvoltage protection resistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B17/00—Insulators or insulating bodies characterised by their form
- H01B17/42—Means for obtaining improved distribution of voltage; Protection against arc discharges
- H01B17/46—Means for providing an external arc-discharge path
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T1/00—Details of spark gaps
- H01T1/16—Series resistor structurally associated with spark gap
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Insulators (AREA)
- Thermistors And Varistors (AREA)
Abstract
LIGHTENING ARRESTOR INSULATOR
AND METHOD OF PRODUCING THE SAME
Abstract of the Disclosure An excellent lightening arrestor insulator is provided having a discharge gap portion and an arrestor ZnO element device both built in a body of the insulator, comprising projected discharge electrodes arranged in the inside of the insulator body, the discharge gap portion being formed of a heat resistant protrusion arranged in the inside of the insulator body and surrounding the discharge electrodes, and a pair of metal plates and/or electrically conductive ceramic plates sandwiching the protrusion from both sides thereof and electrically connected to the discharge electrodes, and the pair of plates being joined and airtightly sealed to the protrusion via an inorganic glass. The arrestor ZnO element device has a highly reliable airtight fixing and sealing structure so that accidental troubles in a power supply or distribution line at a normal working voltage can be substantially eliminated, and damages caused by hygromeration and lightenings can be noticeably decreased.
AND METHOD OF PRODUCING THE SAME
Abstract of the Disclosure An excellent lightening arrestor insulator is provided having a discharge gap portion and an arrestor ZnO element device both built in a body of the insulator, comprising projected discharge electrodes arranged in the inside of the insulator body, the discharge gap portion being formed of a heat resistant protrusion arranged in the inside of the insulator body and surrounding the discharge electrodes, and a pair of metal plates and/or electrically conductive ceramic plates sandwiching the protrusion from both sides thereof and electrically connected to the discharge electrodes, and the pair of plates being joined and airtightly sealed to the protrusion via an inorganic glass. The arrestor ZnO element device has a highly reliable airtight fixing and sealing structure so that accidental troubles in a power supply or distribution line at a normal working voltage can be substantially eliminated, and damages caused by hygromeration and lightenings can be noticeably decreased.
Description
~` ~3317~1 LIGHTENING ARRESTOR INSULATOR
AND METHOD OF PRODUCING THE SAME
~ he present invention relates to a lightening arrestor insulator having a lightening absorber portion consisting of ZnO element and a discharge gap portion booth built in a body of the insulator, and a method of 05 producing the same.
Heretofore, a lightening arrestor insulator having a lightening absorber portion consisting of ZnO
element and a discharge gap portion booth built in a body of the insulator has been known, wherein the discharge gap portion performs discharging at a voltage sufficiently lower than insulative ensuarance of a transformer or a so-called cut-out apparatus to be protected to let off the lightening current to the earth so as to protect the transformer or the like at the time of lightening, and the ZnO element functions to restore instantaneously the electrical insulation of the gap portion to interrupt the electric current flow after the discharging of the discharge gap portion. . ~.
An example of such lightening arrestor insulator .;~ :.
is disclosed in Japanese Utility Model Application Publication No. 52-17,719, wherein the gap portion and the.ZnO element are arranged in the insulator body, and the insulator body is capped by a ceramic cap by means .~-~
~ ~ . :
: 2 ~ .. ~
~: ` ::
i ';~ l 7~ 1 of threading or an O-ring.
However, the lightening arrestor insulator of the Japanese Utility Model Application Publication No. 52-17,719 connects the inside arrangements by mere 05 mechanical means, so that it has a drawback in that, if once an air-tight sealing of the ceramic cap is broken, the inside of the insulator body is humidized to incur an accidental trouble in a power distribution line at a normal working voltage, particularly due to hygromera-tion of the discharge gap portion.
Heretofore, also a lightening arrestor insulatorhas been used having a lightening arrestor function of firmly gripping a power supply line and decreasing an accidental trouble in the power supply line at the time 16 of direct hit of a lightening.
An example of such insulator and a method of producing the same is disclosed in the applicants' Japanese Patent Application Laid-Open No. 57-160,555, wherein the ZnO element, which protects the insulator per se from an excessively large electric current at the tine of hit of a lightening, is integrally fixed and sealed in the inside of the insulator by means of an `: :
inorganic glass. The insulator has a characteristic feature~of superior airtight sealing and electric ~-26 insulation properties.
However, in the method of producing the above , .
:
.. . . . .
, 1 7 ~ 1 insulator, the whole of the insulator is heated and retained in a large homogeneous heating furnace such as an electric furnace, while casting an inorganic glass thereinto, so that production efficiency is bad and an 05 annealing process and other processes are necessary after the casting of the inorganic glass in the insulator. Therefore, the production method requires a large furnace and a long time for the sealing, and cannot produce insulators efficiently because number of insulators that can be produced in the furnace in one sealing operation is restricted by an inner volume of the furnace.
An object of the present invention is to obviate the above drawbacks.
An other object of the present invention is to provide a splendid lightening arrestor insulator having a high reliability and not having an accidental trouble in a power distribution line at a normal working voltage and hence can reduce the troubles caused by lightenings.
Another object of the present invention is to provide a lightening arrestor insulator having an excellently fixed and airtightly sealed discharge gap ~ -portion.
Still another object of the present invention is - : :-~6 to provide a lightening arrestor insulator having an -~
excellently fixed and airtightly sealed arrestor ZnO
~31781 element device.
A further object of the present invention is to provide a lightening arrestor insulator having both the excellently ~ixed and airtightly sealed discharge gap 05 portion and the excellently fixed airtightly sealed arrestor ZnO element device.
Still further object of the present invention is to provide a method of producing a lightening arrestor insulator having electrodes and an arrestor ZnO element device in a body of the insulator, wherein the fixing and sealing of the arrestor ZnO element device composed of an arrestor ZnO element and electrically condctive covers actings as the electrodes by means of an inorganic glass can be put into effect simply by partial lff heating of the insulator.
Another object of the present invention is to provide a method of producing a lightening arrestor insulator having a lightening arrestor function, an airtight sealing property, and an electrical insulative property promptly by a simple and economical apparatus, and which can, if desired, control freely an environ-mentai atmosphere around an arrestor ZnO element device , ~ :
built therein.
The present invention is a lightening arrestor insulator having a discharge gap portion and an arrestor ZnO element device both built in a body of the , : .
.
., : .
insulator, comprising projected discharge electrodes arranged in the inside of the insulator body, the discharge gap portion being formed of a heat resistant protrusion arranged in the inside of the insulator body 05 and surrounding the discharge electrodes, and a pair of metal plates and/or electrically conductive ceramic plates sandwitching the protrusion from both sides thereof and electrically connected to the discharge electrodes, and the pair of plates being joined and airtightly sealed to the protrusion via an inorganic glass.
The heat resistant protrusion may be a separate or integral part of the insulator body.
In another aspect, the present invention is also : 16 a lightening arrestor insulator baving electrodes and an arrestor ZnO element device both built in a body of tbe :~
insulator, wherein the arrestor ZnO element device~being -~
formed of an arrestor~ZnO element, the insulator:body surrounding the arrestor ZnO~e1ement,~and metallio~
20 covers~and/or electrically conductive ceramic covers :~
acting~a3~the~eleotrodes~and:3andwitohing the arrestor~
ZnO~elèment from both:sides tbereof, the covers being;
oined and;airtightly~sealed~vla an:inorganic glass.
The present invention is also a metbod of 25~producing a lightening arrestor~insulator having an arrestor ZnO element device and a discbarge gap portion ~ ~ .
-- u --both built in a body of the insulator, wherein a pair of metal plates and/or electrically conductive ceramic plates are electrically connected to projected discharge electrodes, disposed to sandwich and contact with a OS protrusion surrounding the discharge electrodes via an inorganic glass, and then heated by induction heating to melt the inorganic glass so as to join the pair of metal plate and/or electrically conductive ceramic plate and the protrusion by the molten glass, thereby to form an airtight sealing of the discharge gap portion.
The formed airtight sealing of the discharge gap portion has a high reliability in that the pair of plates having the discharge electrodes is directly joined to the protrusion by means of an inorganic glass.
1~ By this arrangement, the lightening arrestor insulator of the present invention exhibits equivalent functions to those of conventional lightening arrestor insulator, and still prevents an accidental trouble in a power distribution line at a normal working voltage as well as hygromeration of the discharge gap portion due to accidental deterioration of the airtight sealing of the discharge gap, because the discharge gap portion is integrally fixed and airtightly sealed to the insulator ' body.
As a result, the lightening arrestor insulator of the present invention can widely decrease troubles ' .
.
~ -7-~`
. . -, ~ .
~ 1331781 caused by lightenings and increase reliability of power supply.
In case of joining the discharge gap portion and the insulator body via the pair of plates by means of an 05 inorganic glass, the pair of plates is heated by an induction heating and the glass is substantially solely melted to airtightly seal the discharge gap portion, so that the temperature of the whole insulator is not increased. ~herefore, a known phenomenon can not occur 10 that an inner pressure within the discharge gap is left -reduced after solidification of the molten glass which is always seen in a conventional method of joining the discharge gap portion and the insulator body by heating the whole of the insulator, and the inner pressure 15 within the discharge gap portion is substantially not ~;
reduced even after the formation of the airtightly sealed discharge gap portion. As a result, as compared with a necessity of increasing a distance between the discharge electrodes corresponding to a decrease of the : :
inner pressure within the discharge gap portion in conventional methods for obtaining a constant discharge voltage can be obviated, so that the distance between the discharge electrodes can be made small, and the lightening protective insulators can be produced cheaply :~
: 2~ without requiring conventional post treatments of ;;~:~
controlling the inner pressure within the discharge gap ~ , :
through a hole and sealing the hole.
The present invention is also a method of producing a lightening arrestor insulator having electrodes and an arrestor ZnO element device formed of 05 an arrestor ZnO element and metallic covers and/or electrically conductive ceramic covers acting as the electrodes airtightly fixed and sealed in a cavity of the insulator body, wherein the covers are provided on the upper and bottom surfaces of the ZnO element, mounted and pressed on the insulator body via an inorganic glass, and then the glass is heated and melted by induction heating so as to form an airtight fixing ;$~
and sealing between the covers and the insulator body after solidification of the molten glass.
In this method, airtight sealing and fixing of the covers can be achieved by partial heating of the insulator, and an environmental atmosphere around the :~ ZnO element can be adjusted in that the covers are made of an:electrically conductive material and induction heated by a high frequency induction heating, for : example.
For a better understanding of the present `
invention, reference is made to the accompanying drawings, in which:
: ~ Figs. la and lb are a partial crosssectional view~ of an example of the lightening arrestor insulator g : `~
: : ~
.. 133l78~
of the present invention and an enlarged crosssectional view of the discharge gap portion thereof, respectively;
Figs. 2a and 2b are a partial crosssectional view of another example of the lightening arrestor 05 insulator of the present invention and an enlarged crosssectional view of the discharge gap portion thereof, respectively;
Figs. 3a and 3b are explanational views illustrating the method of producing the lightening 10 arrestor insulator having a built in discharge gap -portion of the present invention, respectively; ;;~
Fig. 4 is a schematic view partly in crossection of an example of the lightening arrestor insulator of the present insulator; and Fig. 5 is a schematic view partly in crosssection of another example of the lightening arrestor insulator of the present insulator.
Numberings in the drawings.
l ....... insulator body 20 la ...... upper end of insulator body l lb;...... lower end of insulator body l 2 ...... protrusion ;~
3a, 3b .. .....discharge electrode 4a, 4b ... metal plate 26 5 ... arrestor ZnO element 6 ... electrically conductive member .
.
1 33 1 7~ 1 . ~., 7a, 7b ... resilient member 8a, 8b ... metallic cap 9 ... filler 10a, 10b ... inorganic glass 05 lla, llb ... tapered surface 12a, 12b ... electrically conductive ceramic plate 13 ... induction coil 14 .... pressing portion ' !~, 15 ... auxiliary stainless rod 16 ... ceramic cylinder 17a, 17b ... metallic or electrically conductive ceramic cover 20 ... inorganic fibers 21 ... resilient electrically conductive material 1~ Referring to Figs. la and lb showing an embodiment of the present insulator, an insulator body 1 is provided with a cylindrical protrusion 2 integrally ormed with the insulator body 1 at the inner upper portion thereof, the protrusion 2 is sandwiched by metal plates 4a, 4b~having projected discharge electrodes 3a, ~3b and airtightly joined and sealed by inorganic glasses 10a,;~10b, to form a discharge gap portion as shown in Fig.' lb. The discharge gap portion is provided with an arrestor ZnO element 5 thereabove, and an electrically ~25 conductive member 6 therebelow, arranged in this order, and the ZnO element 5 and the electrically conductive , ::
=, _ . ~. ,... . ... . :, ~ . . . ..
member 6 are connected to the insulator body 1 via resilient members 7a, 7b by metallic caps 8a, 8b, to form a lightening arrestor insulator of the present invention. In the spaces formed between the insulator 06 body 1 and the ZnO element 5 and between the insulator body 1 and the electrically conductive member 6 is filled a filler 9 such as inorganic fibers. As the metal plates 4a, 4b, at least one of Kovar, stainless steel, aluminum, nickel, nickel-iron alloy and silver is used. Preferably, those metals having thermal expansion coefficients approximately to that of the insulator body 1 are used.
Referring to Figs. 2a and 2b showing another embodiment of the present insulator, the same elements 16 with Figs. la and lb are numbered with the same reference numbers, and explanations thereof are omitted.
:: ~
In this embodiment, different from the embodiment shown;~
in Figs. la and lb, the protrusion 2 is made of tapered surfaces lla, llb separately made from the insulator -~
ao body 1, and the tapered surfaces lla, llb are joined to electrically conductive ceramic plates 12a, 12b via inorganic glasses 10a, 10b, to form a discharge gap portion as shown in Fig. 2b. Further, in this embodi=ent, a ceramic cylinder 16 is disposed between 26 the eIectrically~conductive ceramic plates 12a, 12b to surround the discharge electrodes 12a, 12b so as to T~ n ~r k .
. , , . , . ~ . , .. ~ .. . .. . ..... . ..
reinforce the strength of the discharge gap portion.
In addition, the ZnO element 5 and the electrically conductive member 6 are arranged in different order in the cavity of the insulator body 1, however, this 05 embodiment can achieve similar effects as those of the embodiment of Fig. 1. As the electrically conductive plates 12a, 12b, preferably use is made of at least one of zirconium boride, zinc oxide, stannous oxide, graphite, and silicon carbide.
Referring to Figs. 3a and 3b each showing another embodiment of the present insulator, a metal plate 4a having a projected discharge electrode 3a is disposed on a protrusion 2 via an inorganic glass 10a in such a fashion that the discharge electrode 3a comes to 1~ face the protrusion 2, then an induction coil 13 is mounted on the metal plate 4a, and an electric current is passed through the induction coil 13 to heat the inorganic glass 10a by induction heating so as to join the metal plate 4a to the protrusion 2, as shown in Fig. 3a. After completion of the joining of the metal pIate 4a, the metal plate 4b is joined to the protrusion 2 in the same way to form a discharge gap portion.
In the embodiment shown ir. Fig. 3b, the metal plates 4a, 4b are joined to the protrusion 2 by using an 2~ auxiliary stainless steel rod 15 having a pressing portion 14 arranged through the cavity of the insulator ~, :
: :
. . . ~, . . . .
body 2, in addition to the use of the induction coil 13.
This embodiment i5 more preferable, because the metal plates 4a, 4b can be pressed by the pressing portion 14 of the stainless steel rod 15 at the time of induction 05 heating. In either embodiment, the inorganic glass 10a, 10b can be applied in a powder form or a paste form on ~ -the metal plates 4a, 4b or the protrusion 2. Instead of the metal plates used in the above embodiments of induction heating, electrically conductive ceramic plates or a pair of a metal plate and an electrically conductive ceramic plate can be used in the similar way to achieve the airtight fixing and sealing of the discharged gap portion to the same extent of effect by means of the inorganic glass.
15Referring to Fig. 4 showing an embodiment of a -~
lightening arrestor insulator of in the present invention, the insulator body 1 accommodates in its cavity a columnar arrestor ZnO element 5 consisting essentially of ZnO in airtight state to form a lightening arrestor insulator of the present invention.
More particularly, the upper and the lower end portions la, lb of the inaulator body 1 are respectively sealed airtightly by metallic covers 17a, 17b acting as electrodes via inorganic glasses 10a, 10b. A ceramic Z~ cylinder 16 and inorganic fibers 20 are disposed as reinforcing members in a space between the side wall of .
:
- 1 33 ~ 78 i the arrestor ZnO element 5 and the inner wall of the insulator body 1 for protecting the insulator body by mitigating an increase of the inner pressure caused by extraordinary large current due to direct hit of a ~ lightening through deteriorated ZnO element. Further, a resilient electrically conductive material 21 is disposed between the arrestor ZnO element 5 and the upper end cover 17a, in order to mitigate an external stress which is always exerted on the lightening 10 arrestor insulator from the exterior. In this embodiment, the covers 17a, 17b function as the electrodes, so that the projected electrodes as shown in Fig. lb may be dispensed with.
Referring to Fig. 5 showing another embodiment 15 of a lightening arrestor insulator of the present invention, the upper and the lower end portions of the insulator body 1 are sealed airtightly by electrically conductive ceramic covers 17a, 17b via an inorganic glass 10a, 10b, the covers acting as the electrodes.
In either structure of Figs. 4 and 5, the upper and the lower end portions of the insulator body 1 are sealed airtightly to the metallic or the electrically conductive ceramic covers 17a, 17b via the inorganic 2~ glass 10a, 10b. Therefore, an inorganic glass have to be applied in various methods on the surfaces of the : ~ ;
, ,.. ~ ~ . , . ,,, .... . .. , . .. , :
metallic covers and/or the ceramic covers which are to be contacted to each other. Illustrative examples of such application methods are heretofore known methods of directly applying a glass powder, a spray method, a 06 paste method, and a tape method. After the application of the glass, the upper cover 17a and the lower cover 17b are mounted on the arrestor ZnO element 5 and the insulator body 1 from the both sides thereof, pressed thereon, and induction heated to melt the inorganic glass 10a, 10b so as to form airtight sealings between the upper metallic cover 17a and the upper end la of the insulator body 1 and between the lower metallic cover 17b and the lower end lb of the insulator body 1 for the embodiment shown in Fig. 4.
For the heating of the glass, a high frequency induction heating of the upper and the lower covers can be adopted for the covers are made of an electrically conductive material. If the heating is effected by a high frequency induction heating, a heating apparatus of a large scale is not necessary, and partial heating of insulators solely at the covers can be effected, and an - environmental atmosphere and an inner pressure of the : ~ ~
atmosphere around the arrestor ZnO element 5 can be adjusted freely. Thus, the inner pressure can be adjusted to a preferable pressure of 1-10 atm, and a highly electrically insulative gas, such as SF6, can be ~ .
: '.' ' - 16- ~-~; '' .
. ,. ; ~ . .,...... . - - ~ ., .
1 33~7~1 used and sealed as the atmosphere. In this case, the portions to be heated of the insulator can be localized or restricted, so that a fiber reinfoxced plastics (FRP) can be used as the reinforcing member 16. In order to 05 enhance the joining, preferably, the metallic covers are preliminarily heated up to 800-1,000C in an oxidizing atmosphere to form a coating of an oxide on the surfaces thereof, more preferably, the portions of the covers to be joined are preliminarily coated with an inorganic glass and fired prior to the joining.
Hereinafter, the explanations will be made in more detail with reference to examples.
Example 1 Inorganic glasses having the compositions and the characteristic properties as shown in the following Table 1 are used in combination with various metallic plates as shown in the following Table 2, and induction heated to form discharge gap portions of the shapes as described în Table 2. Thus formed discharge gap portions theiroelves, and those after sub~ected to a cooling and heating test of thrice reciprocal cooling at ; -20C and heating at 80C, are tested on an airtight sealness test by means of He gas leakage measurement.
The results are shown also in Table 2. In Table 2, 2~ symbol O represents those insulators that did not show a leakage of He gas, and symbol x represents those :~ :
. -.- ` ~ ' : ' " . .
7 ~ 1 insulators that show a leakage of He gas. A condition of the He gas leakage test is lxlO-9 atm. cc/sec or more.
' - ~
~; :
'' ' ' ' ~' , ~ 25 : :
~, -- -:, `~ - 18-1 ,. . . ~ ~ , .. ,~ ' V u~ lo~ In O
o o~
¦~1 ~ O O N ~
o T o l o~
~1 ¦ U, 3 ~ ~ o ~.
u o ~o o o~ ~
o .C
m O O O m o o~ .
. ; ~ O O o .
. _ ~ ~ .a~
'o _ o :
' : : C~ o ~ .~ .~ Q. ~ C~ .
E~o'~ qO~ O e O ~ t~
_ ~ ~q _ ~ E~ ~ ~q :
::
:: ~: :` ::::
- ~ 1 331 781 ;~ r ~ O O O O O O O O O O O X X
. ~ _ _ _ _ ~ - o o o o o o o o o o o ~ o C ) ~0 ~D ~D t` 1~ N N 1~ 1~ U:~ ~ ~D I_ ~0 r ~r ~ ~ r O` ~ ~ r ~ ~ ~ ~
Nl ~ ¦ eC I ~ I
E~ ~ u~ o In U~ O U~ O O O O O U~ U~
~: ~
. ~ 1~ tU ~ ~ R ~ Q 1~ ~ nl ~ ~1 1~ ~ ~;
Z _ _ _ _ _ ~ N
V ~1 ~ r~ ~ 117 ~D ~ -- ~1 a ~;
317~1 As seen clearly from the results of Table 2, the metallic plates are substantially completely joined and sealed by means of inorganic glasses. However, the combinations of the copper plate and the PbO B203 series 05 glass of type A, and the niobium plate and the B203-ZnO
series glass of type I, are insufficiently sealed, showing a leakage of He gas.
Example 2 The various inorganic glasses shown in the above Table l are used in combination with various electrically conductive ceramic plates as shown in the following Table 3, and induction heated to form discharge gap portions. Thus formed discharge gap portions theirselves, and those after the cooling and - 15 heating test, are tested on the same airtight sealness test as in Example l. The results are shown in the following Table 3. ~-- ~
: - 21-~`
:
.. .... , .. . . ~ .. .. ... .. . .. . ..
' ' ' ~ ~ "' ' ' ' ' . ' ' ` ' `
-- , ~: ' ' .
,::, .," '';,,, "".'' .:', ' ~' ~ ' .
:.'.. : ' : .'.. . ... '. ' - . .
3t7~1 1~ 1-` ~
. E~ 1: O O O O O O O O O X X x X
~u o o o o o o o o o o o o o ~ o o ~ ~ ~o ~ o I~ ~` r` o N I~ I~ 1~') e~ O ~ ~ .r ~ ~ ~ .. oD .r ~ v I ~
E~ .U~ ~ ,1 u~ ~ u~ u~ ,ol In U~ ~O Ul U7 U~ -' ~. ~, ~
¦ :~ ¦ N ~ N ¦ N ~ O ¦ U ¦ ~J ¦ e ~ ~
a~ _l ~ ___ ~ _ _ _ IZ I'~ 1~
~I ~I ~I ~I _l ~t ~I ~I ~ 1: ~ Ç
:~ ~ __ ~; ~: ~: ~a 1 33 ~ 78 ~
As seen clearly from the results of the above Table 3, the electrically conductive ceramic plates are substantially completely joined and sealed by means of inorganic glasses. However, the combinations of the OS plate of molybdenum silicide, tungsten carbide, or chromium oxide and the glasses of Reference 3-6, are insufficiently sealed, showing a leakage of He gas.
Example 3 In order to examine the state of the induction heating in the method of the present invention, the various inorganic glasses shown in the above Table l are disposed between the protrusions of the insulator bodies and metal plates or electrically conductive ceramic plates shown in the following Table 4 in the forms as 16 described in Table 4, and induction heated in conditions as described also in Table 4 to form discharge gap portions. Thus formed discharge gap portions theirselves, and those after the cooling and heating test, are tested on the same airtight sealness test as in Example l. The results are shown in the following Table 4.
~ ;' - : ; ~ - ~:: .,: :.
;...... . . . . .
. : . :::~ -; - . ~ - .
~ .
~ ~3 1 78 1 . ` .
I` ~- ~I;'r;~l 1;1 v v~ o o o o o o ~o o o O E~ _ O O O O O N ~ O N
1~: ~:: ~1 _~ ~1 _1 _1 ~1 ~__ ~1 O ' ~' JJ ~a- o o o o o o o o o o o ~ ~ P O O O O O O O O O O O
P: p _ ~1 ~1 ~1 ~1 ~ ~ ~1 ~ ~ ~1 ~/
_ _ O O OO O ..
h~ 1~~ ~
s~ ~(~ ~) ~ a) a~ a) ~ (~U~ ~11 ~ t~ o E~ ~ ~: ~a .~ ~a ~ ~ x ~ x ~ ~c ~ x ~ x ~ ~
H t~ ~ t~ ~a ~ ~a 111 1~ 1~
Ul U~ U~ Ul U~ ., = = C O u ~I = = = = ~3 = = = ..
OU ~ eS ~ ~ __ ~ ~ ~ m m a~
o = ~ ~3 ~ ~ ~. o u~. u~. o. ~. o o o o. ~o -~
IE~o=l~ 1~ l~olyl~T~o~
_ _ _ _ N N N N
'O~ ~ ~ ~ = ~= = = ~ ~ ~
___ _ ___ ___ ~ ~-1 ~,,",,,,,"- ~ ,.,,."", ,,,,",,`i~;, :-;. ~ . i .. ` . ~
AS seen from the results of Table 4, substan-tially completely joined and sealed discharge gap portions can be formed. However, in case where a stainless steel rod is not used and induction heating is 05 effected for a short time using powdery inorganic glass, the formed discharge gap portions show some leakage of He gas in the airtight sealness test after the cooling and heating.
Example 4 10The lightening arrestor insulators as shown in : Figs. la and lb are produced by preparing arrestor ZnO
element devices of Test Nos. 1-6 of the following Table 5 by using an inorganic glass and various sealing structures and structural conditions as shown in the ~ 16 following Table 5.
,;
` ~ ~20 ~ ' ~
~ i ~
:
317~1 6 ~ E 6 6 6 6 8 ~
O V U ~D CO IS7 N L'l ~0 _ 9 9 ~ 6 E 1~ L
a ~; 6 ~IZ 9 D 1 ~
I:o'V I.:DI I I 1~ ~
s= o ~ = a ,,, ~, v ~ ~ ~ ~ Q .~ ~ ~ ~
u~ t~ ~ R . ~iS u~ S v Z __ _ ~
E~ _l c~l ~ ~r In ~ ~V
~ __ O
~ 13317~1 AS seen from the above Table 5, various sealing covers and reinforcing members can be used, and environmental atmosphere around the ZnO element can be adjusted. These sealing covers and reinforcing members 05 can be sealed in a short time by high frequency induction heating of the electrically conductive sealing covers.
As apparent from the above foregoing explanations, the lightening arrestor insulator of the present invention has a discharge gap portion formed by directly joining a protrusion arranged in the inside of the insulator body and metal plates and/or electrically conductive ceramic plates having discharge electrodes by means of an inorganic glass, so that lightening arrestor 1~ insulators having a highly reliable airtightly sealed discharge gap portion can be obtained. As a result, accidental troubles in a power service line at a normal working voltage can be substantially eliminated, and damages caused by hygromeration can be noticeably decreased, so that electric power can be supplied with widely improved reliability.
Also, the lightening arrestor insulator of the present invention has electrodes and an arrestor ZnO
element~ device formed by directly joining the inside of the insulator body and metallic covers and/or electrically conductive covers acting as the electrodes ~ ~ ;
, - . .. .
13317~1 by means of an inorganic glass, so that lightening arrestor insulators having a highly reliable airtightly sealed arrestor ZnO element device can be obtained.
As a result, accidental troubles in a power service line 06 at a normal working voltage can be substantially eliminated, and damages caused by lightenings can be noticeably decreased, so that electric power can be supplied with widely improved reliability, from this aspect too.
According to the method of the present invention, the discharge gap portion is formed and sealed airtightly by partial heating of the lightening arrestor insulator by means of an induction heating, so that temperature rise of the whole insulator can be 16 avoided. As a result, an inner pressure within the discharge gap portion is not changed substantially after the airtight sealing, and lightening arrestor insulators of the desired properties can easily be obtained.
Also, according to the method of the present invention, the arrestor ZnO element device is formed and ~ sealed airtightly by partial heating of the lightening ; ~ arrestor insulator by means of an induction heating solely of the upper and lower electrically conductive -covers sandwiching the arrestor ZnO element via an 26 inorganic glass, so that a position of breakage of the ;~ insulator at the time of hit of a lightening can be ~ ~ .
~ - 28-: , ~ , .
~ ;, - ~ .
1 3 ~ ~ 7~ 1 restricted to the covers accommodating the arrestor ZnO
element. As a result, a crack formed in the covers can be prevented from developing to the insulator body, and discharge characteristic properties of the insulator at 06 the time of short-cut of an extraordinary excessive electric current can be improved.
In addition, a heating device in an apparatus for producing the lightening arrestor insulator can be minimized, and an environmental atmosphere around the arrestor ZnO element can be adjusted to desired ones.
Though the contacting end surfaces of the upper and lower covers and the insulator body are shown as tapered surfaces in the above embodiments, the contacting end surfaces may have another shapes, such as shown in Fig. 5.
The present invention is not limited to a suspension type lightening arrestor insulator, and clearly applicable to other shapes of lightening arrestor insulators.
Although the present invention has been explained with specific examples, it is of course àppa~rent to those skil}ed in the art that various changes and modifications thereof are possible without departing from the broad spirit and aspect of the present invention as defined in the appended claims.
~; :
AND METHOD OF PRODUCING THE SAME
~ he present invention relates to a lightening arrestor insulator having a lightening absorber portion consisting of ZnO element and a discharge gap portion booth built in a body of the insulator, and a method of 05 producing the same.
Heretofore, a lightening arrestor insulator having a lightening absorber portion consisting of ZnO
element and a discharge gap portion booth built in a body of the insulator has been known, wherein the discharge gap portion performs discharging at a voltage sufficiently lower than insulative ensuarance of a transformer or a so-called cut-out apparatus to be protected to let off the lightening current to the earth so as to protect the transformer or the like at the time of lightening, and the ZnO element functions to restore instantaneously the electrical insulation of the gap portion to interrupt the electric current flow after the discharging of the discharge gap portion. . ~.
An example of such lightening arrestor insulator .;~ :.
is disclosed in Japanese Utility Model Application Publication No. 52-17,719, wherein the gap portion and the.ZnO element are arranged in the insulator body, and the insulator body is capped by a ceramic cap by means .~-~
~ ~ . :
: 2 ~ .. ~
~: ` ::
i ';~ l 7~ 1 of threading or an O-ring.
However, the lightening arrestor insulator of the Japanese Utility Model Application Publication No. 52-17,719 connects the inside arrangements by mere 05 mechanical means, so that it has a drawback in that, if once an air-tight sealing of the ceramic cap is broken, the inside of the insulator body is humidized to incur an accidental trouble in a power distribution line at a normal working voltage, particularly due to hygromera-tion of the discharge gap portion.
Heretofore, also a lightening arrestor insulatorhas been used having a lightening arrestor function of firmly gripping a power supply line and decreasing an accidental trouble in the power supply line at the time 16 of direct hit of a lightening.
An example of such insulator and a method of producing the same is disclosed in the applicants' Japanese Patent Application Laid-Open No. 57-160,555, wherein the ZnO element, which protects the insulator per se from an excessively large electric current at the tine of hit of a lightening, is integrally fixed and sealed in the inside of the insulator by means of an `: :
inorganic glass. The insulator has a characteristic feature~of superior airtight sealing and electric ~-26 insulation properties.
However, in the method of producing the above , .
:
.. . . . .
, 1 7 ~ 1 insulator, the whole of the insulator is heated and retained in a large homogeneous heating furnace such as an electric furnace, while casting an inorganic glass thereinto, so that production efficiency is bad and an 05 annealing process and other processes are necessary after the casting of the inorganic glass in the insulator. Therefore, the production method requires a large furnace and a long time for the sealing, and cannot produce insulators efficiently because number of insulators that can be produced in the furnace in one sealing operation is restricted by an inner volume of the furnace.
An object of the present invention is to obviate the above drawbacks.
An other object of the present invention is to provide a splendid lightening arrestor insulator having a high reliability and not having an accidental trouble in a power distribution line at a normal working voltage and hence can reduce the troubles caused by lightenings.
Another object of the present invention is to provide a lightening arrestor insulator having an excellently fixed and airtightly sealed discharge gap ~ -portion.
Still another object of the present invention is - : :-~6 to provide a lightening arrestor insulator having an -~
excellently fixed and airtightly sealed arrestor ZnO
~31781 element device.
A further object of the present invention is to provide a lightening arrestor insulator having both the excellently ~ixed and airtightly sealed discharge gap 05 portion and the excellently fixed airtightly sealed arrestor ZnO element device.
Still further object of the present invention is to provide a method of producing a lightening arrestor insulator having electrodes and an arrestor ZnO element device in a body of the insulator, wherein the fixing and sealing of the arrestor ZnO element device composed of an arrestor ZnO element and electrically condctive covers actings as the electrodes by means of an inorganic glass can be put into effect simply by partial lff heating of the insulator.
Another object of the present invention is to provide a method of producing a lightening arrestor insulator having a lightening arrestor function, an airtight sealing property, and an electrical insulative property promptly by a simple and economical apparatus, and which can, if desired, control freely an environ-mentai atmosphere around an arrestor ZnO element device , ~ :
built therein.
The present invention is a lightening arrestor insulator having a discharge gap portion and an arrestor ZnO element device both built in a body of the , : .
.
., : .
insulator, comprising projected discharge electrodes arranged in the inside of the insulator body, the discharge gap portion being formed of a heat resistant protrusion arranged in the inside of the insulator body 05 and surrounding the discharge electrodes, and a pair of metal plates and/or electrically conductive ceramic plates sandwitching the protrusion from both sides thereof and electrically connected to the discharge electrodes, and the pair of plates being joined and airtightly sealed to the protrusion via an inorganic glass.
The heat resistant protrusion may be a separate or integral part of the insulator body.
In another aspect, the present invention is also : 16 a lightening arrestor insulator baving electrodes and an arrestor ZnO element device both built in a body of tbe :~
insulator, wherein the arrestor ZnO element device~being -~
formed of an arrestor~ZnO element, the insulator:body surrounding the arrestor ZnO~e1ement,~and metallio~
20 covers~and/or electrically conductive ceramic covers :~
acting~a3~the~eleotrodes~and:3andwitohing the arrestor~
ZnO~elèment from both:sides tbereof, the covers being;
oined and;airtightly~sealed~vla an:inorganic glass.
The present invention is also a metbod of 25~producing a lightening arrestor~insulator having an arrestor ZnO element device and a discbarge gap portion ~ ~ .
-- u --both built in a body of the insulator, wherein a pair of metal plates and/or electrically conductive ceramic plates are electrically connected to projected discharge electrodes, disposed to sandwich and contact with a OS protrusion surrounding the discharge electrodes via an inorganic glass, and then heated by induction heating to melt the inorganic glass so as to join the pair of metal plate and/or electrically conductive ceramic plate and the protrusion by the molten glass, thereby to form an airtight sealing of the discharge gap portion.
The formed airtight sealing of the discharge gap portion has a high reliability in that the pair of plates having the discharge electrodes is directly joined to the protrusion by means of an inorganic glass.
1~ By this arrangement, the lightening arrestor insulator of the present invention exhibits equivalent functions to those of conventional lightening arrestor insulator, and still prevents an accidental trouble in a power distribution line at a normal working voltage as well as hygromeration of the discharge gap portion due to accidental deterioration of the airtight sealing of the discharge gap, because the discharge gap portion is integrally fixed and airtightly sealed to the insulator ' body.
As a result, the lightening arrestor insulator of the present invention can widely decrease troubles ' .
.
~ -7-~`
. . -, ~ .
~ 1331781 caused by lightenings and increase reliability of power supply.
In case of joining the discharge gap portion and the insulator body via the pair of plates by means of an 05 inorganic glass, the pair of plates is heated by an induction heating and the glass is substantially solely melted to airtightly seal the discharge gap portion, so that the temperature of the whole insulator is not increased. ~herefore, a known phenomenon can not occur 10 that an inner pressure within the discharge gap is left -reduced after solidification of the molten glass which is always seen in a conventional method of joining the discharge gap portion and the insulator body by heating the whole of the insulator, and the inner pressure 15 within the discharge gap portion is substantially not ~;
reduced even after the formation of the airtightly sealed discharge gap portion. As a result, as compared with a necessity of increasing a distance between the discharge electrodes corresponding to a decrease of the : :
inner pressure within the discharge gap portion in conventional methods for obtaining a constant discharge voltage can be obviated, so that the distance between the discharge electrodes can be made small, and the lightening protective insulators can be produced cheaply :~
: 2~ without requiring conventional post treatments of ;;~:~
controlling the inner pressure within the discharge gap ~ , :
through a hole and sealing the hole.
The present invention is also a method of producing a lightening arrestor insulator having electrodes and an arrestor ZnO element device formed of 05 an arrestor ZnO element and metallic covers and/or electrically conductive ceramic covers acting as the electrodes airtightly fixed and sealed in a cavity of the insulator body, wherein the covers are provided on the upper and bottom surfaces of the ZnO element, mounted and pressed on the insulator body via an inorganic glass, and then the glass is heated and melted by induction heating so as to form an airtight fixing ;$~
and sealing between the covers and the insulator body after solidification of the molten glass.
In this method, airtight sealing and fixing of the covers can be achieved by partial heating of the insulator, and an environmental atmosphere around the :~ ZnO element can be adjusted in that the covers are made of an:electrically conductive material and induction heated by a high frequency induction heating, for : example.
For a better understanding of the present `
invention, reference is made to the accompanying drawings, in which:
: ~ Figs. la and lb are a partial crosssectional view~ of an example of the lightening arrestor insulator g : `~
: : ~
.. 133l78~
of the present invention and an enlarged crosssectional view of the discharge gap portion thereof, respectively;
Figs. 2a and 2b are a partial crosssectional view of another example of the lightening arrestor 05 insulator of the present invention and an enlarged crosssectional view of the discharge gap portion thereof, respectively;
Figs. 3a and 3b are explanational views illustrating the method of producing the lightening 10 arrestor insulator having a built in discharge gap -portion of the present invention, respectively; ;;~
Fig. 4 is a schematic view partly in crossection of an example of the lightening arrestor insulator of the present insulator; and Fig. 5 is a schematic view partly in crosssection of another example of the lightening arrestor insulator of the present insulator.
Numberings in the drawings.
l ....... insulator body 20 la ...... upper end of insulator body l lb;...... lower end of insulator body l 2 ...... protrusion ;~
3a, 3b .. .....discharge electrode 4a, 4b ... metal plate 26 5 ... arrestor ZnO element 6 ... electrically conductive member .
.
1 33 1 7~ 1 . ~., 7a, 7b ... resilient member 8a, 8b ... metallic cap 9 ... filler 10a, 10b ... inorganic glass 05 lla, llb ... tapered surface 12a, 12b ... electrically conductive ceramic plate 13 ... induction coil 14 .... pressing portion ' !~, 15 ... auxiliary stainless rod 16 ... ceramic cylinder 17a, 17b ... metallic or electrically conductive ceramic cover 20 ... inorganic fibers 21 ... resilient electrically conductive material 1~ Referring to Figs. la and lb showing an embodiment of the present insulator, an insulator body 1 is provided with a cylindrical protrusion 2 integrally ormed with the insulator body 1 at the inner upper portion thereof, the protrusion 2 is sandwiched by metal plates 4a, 4b~having projected discharge electrodes 3a, ~3b and airtightly joined and sealed by inorganic glasses 10a,;~10b, to form a discharge gap portion as shown in Fig.' lb. The discharge gap portion is provided with an arrestor ZnO element 5 thereabove, and an electrically ~25 conductive member 6 therebelow, arranged in this order, and the ZnO element 5 and the electrically conductive , ::
=, _ . ~. ,... . ... . :, ~ . . . ..
member 6 are connected to the insulator body 1 via resilient members 7a, 7b by metallic caps 8a, 8b, to form a lightening arrestor insulator of the present invention. In the spaces formed between the insulator 06 body 1 and the ZnO element 5 and between the insulator body 1 and the electrically conductive member 6 is filled a filler 9 such as inorganic fibers. As the metal plates 4a, 4b, at least one of Kovar, stainless steel, aluminum, nickel, nickel-iron alloy and silver is used. Preferably, those metals having thermal expansion coefficients approximately to that of the insulator body 1 are used.
Referring to Figs. 2a and 2b showing another embodiment of the present insulator, the same elements 16 with Figs. la and lb are numbered with the same reference numbers, and explanations thereof are omitted.
:: ~
In this embodiment, different from the embodiment shown;~
in Figs. la and lb, the protrusion 2 is made of tapered surfaces lla, llb separately made from the insulator -~
ao body 1, and the tapered surfaces lla, llb are joined to electrically conductive ceramic plates 12a, 12b via inorganic glasses 10a, 10b, to form a discharge gap portion as shown in Fig. 2b. Further, in this embodi=ent, a ceramic cylinder 16 is disposed between 26 the eIectrically~conductive ceramic plates 12a, 12b to surround the discharge electrodes 12a, 12b so as to T~ n ~r k .
. , , . , . ~ . , .. ~ .. . .. . ..... . ..
reinforce the strength of the discharge gap portion.
In addition, the ZnO element 5 and the electrically conductive member 6 are arranged in different order in the cavity of the insulator body 1, however, this 05 embodiment can achieve similar effects as those of the embodiment of Fig. 1. As the electrically conductive plates 12a, 12b, preferably use is made of at least one of zirconium boride, zinc oxide, stannous oxide, graphite, and silicon carbide.
Referring to Figs. 3a and 3b each showing another embodiment of the present insulator, a metal plate 4a having a projected discharge electrode 3a is disposed on a protrusion 2 via an inorganic glass 10a in such a fashion that the discharge electrode 3a comes to 1~ face the protrusion 2, then an induction coil 13 is mounted on the metal plate 4a, and an electric current is passed through the induction coil 13 to heat the inorganic glass 10a by induction heating so as to join the metal plate 4a to the protrusion 2, as shown in Fig. 3a. After completion of the joining of the metal pIate 4a, the metal plate 4b is joined to the protrusion 2 in the same way to form a discharge gap portion.
In the embodiment shown ir. Fig. 3b, the metal plates 4a, 4b are joined to the protrusion 2 by using an 2~ auxiliary stainless steel rod 15 having a pressing portion 14 arranged through the cavity of the insulator ~, :
: :
. . . ~, . . . .
body 2, in addition to the use of the induction coil 13.
This embodiment i5 more preferable, because the metal plates 4a, 4b can be pressed by the pressing portion 14 of the stainless steel rod 15 at the time of induction 05 heating. In either embodiment, the inorganic glass 10a, 10b can be applied in a powder form or a paste form on ~ -the metal plates 4a, 4b or the protrusion 2. Instead of the metal plates used in the above embodiments of induction heating, electrically conductive ceramic plates or a pair of a metal plate and an electrically conductive ceramic plate can be used in the similar way to achieve the airtight fixing and sealing of the discharged gap portion to the same extent of effect by means of the inorganic glass.
15Referring to Fig. 4 showing an embodiment of a -~
lightening arrestor insulator of in the present invention, the insulator body 1 accommodates in its cavity a columnar arrestor ZnO element 5 consisting essentially of ZnO in airtight state to form a lightening arrestor insulator of the present invention.
More particularly, the upper and the lower end portions la, lb of the inaulator body 1 are respectively sealed airtightly by metallic covers 17a, 17b acting as electrodes via inorganic glasses 10a, 10b. A ceramic Z~ cylinder 16 and inorganic fibers 20 are disposed as reinforcing members in a space between the side wall of .
:
- 1 33 ~ 78 i the arrestor ZnO element 5 and the inner wall of the insulator body 1 for protecting the insulator body by mitigating an increase of the inner pressure caused by extraordinary large current due to direct hit of a ~ lightening through deteriorated ZnO element. Further, a resilient electrically conductive material 21 is disposed between the arrestor ZnO element 5 and the upper end cover 17a, in order to mitigate an external stress which is always exerted on the lightening 10 arrestor insulator from the exterior. In this embodiment, the covers 17a, 17b function as the electrodes, so that the projected electrodes as shown in Fig. lb may be dispensed with.
Referring to Fig. 5 showing another embodiment 15 of a lightening arrestor insulator of the present invention, the upper and the lower end portions of the insulator body 1 are sealed airtightly by electrically conductive ceramic covers 17a, 17b via an inorganic glass 10a, 10b, the covers acting as the electrodes.
In either structure of Figs. 4 and 5, the upper and the lower end portions of the insulator body 1 are sealed airtightly to the metallic or the electrically conductive ceramic covers 17a, 17b via the inorganic 2~ glass 10a, 10b. Therefore, an inorganic glass have to be applied in various methods on the surfaces of the : ~ ;
, ,.. ~ ~ . , . ,,, .... . .. , . .. , :
metallic covers and/or the ceramic covers which are to be contacted to each other. Illustrative examples of such application methods are heretofore known methods of directly applying a glass powder, a spray method, a 06 paste method, and a tape method. After the application of the glass, the upper cover 17a and the lower cover 17b are mounted on the arrestor ZnO element 5 and the insulator body 1 from the both sides thereof, pressed thereon, and induction heated to melt the inorganic glass 10a, 10b so as to form airtight sealings between the upper metallic cover 17a and the upper end la of the insulator body 1 and between the lower metallic cover 17b and the lower end lb of the insulator body 1 for the embodiment shown in Fig. 4.
For the heating of the glass, a high frequency induction heating of the upper and the lower covers can be adopted for the covers are made of an electrically conductive material. If the heating is effected by a high frequency induction heating, a heating apparatus of a large scale is not necessary, and partial heating of insulators solely at the covers can be effected, and an - environmental atmosphere and an inner pressure of the : ~ ~
atmosphere around the arrestor ZnO element 5 can be adjusted freely. Thus, the inner pressure can be adjusted to a preferable pressure of 1-10 atm, and a highly electrically insulative gas, such as SF6, can be ~ .
: '.' ' - 16- ~-~; '' .
. ,. ; ~ . .,...... . - - ~ ., .
1 33~7~1 used and sealed as the atmosphere. In this case, the portions to be heated of the insulator can be localized or restricted, so that a fiber reinfoxced plastics (FRP) can be used as the reinforcing member 16. In order to 05 enhance the joining, preferably, the metallic covers are preliminarily heated up to 800-1,000C in an oxidizing atmosphere to form a coating of an oxide on the surfaces thereof, more preferably, the portions of the covers to be joined are preliminarily coated with an inorganic glass and fired prior to the joining.
Hereinafter, the explanations will be made in more detail with reference to examples.
Example 1 Inorganic glasses having the compositions and the characteristic properties as shown in the following Table 1 are used in combination with various metallic plates as shown in the following Table 2, and induction heated to form discharge gap portions of the shapes as described în Table 2. Thus formed discharge gap portions theiroelves, and those after sub~ected to a cooling and heating test of thrice reciprocal cooling at ; -20C and heating at 80C, are tested on an airtight sealness test by means of He gas leakage measurement.
The results are shown also in Table 2. In Table 2, 2~ symbol O represents those insulators that did not show a leakage of He gas, and symbol x represents those :~ :
. -.- ` ~ ' : ' " . .
7 ~ 1 insulators that show a leakage of He gas. A condition of the He gas leakage test is lxlO-9 atm. cc/sec or more.
' - ~
~; :
'' ' ' ' ~' , ~ 25 : :
~, -- -:, `~ - 18-1 ,. . . ~ ~ , .. ,~ ' V u~ lo~ In O
o o~
¦~1 ~ O O N ~
o T o l o~
~1 ¦ U, 3 ~ ~ o ~.
u o ~o o o~ ~
o .C
m O O O m o o~ .
. ; ~ O O o .
. _ ~ ~ .a~
'o _ o :
' : : C~ o ~ .~ .~ Q. ~ C~ .
E~o'~ qO~ O e O ~ t~
_ ~ ~q _ ~ E~ ~ ~q :
::
:: ~: :` ::::
- ~ 1 331 781 ;~ r ~ O O O O O O O O O O O X X
. ~ _ _ _ _ ~ - o o o o o o o o o o o ~ o C ) ~0 ~D ~D t` 1~ N N 1~ 1~ U:~ ~ ~D I_ ~0 r ~r ~ ~ r O` ~ ~ r ~ ~ ~ ~
Nl ~ ¦ eC I ~ I
E~ ~ u~ o In U~ O U~ O O O O O U~ U~
~: ~
. ~ 1~ tU ~ ~ R ~ Q 1~ ~ nl ~ ~1 1~ ~ ~;
Z _ _ _ _ _ ~ N
V ~1 ~ r~ ~ 117 ~D ~ -- ~1 a ~;
317~1 As seen clearly from the results of Table 2, the metallic plates are substantially completely joined and sealed by means of inorganic glasses. However, the combinations of the copper plate and the PbO B203 series 05 glass of type A, and the niobium plate and the B203-ZnO
series glass of type I, are insufficiently sealed, showing a leakage of He gas.
Example 2 The various inorganic glasses shown in the above Table l are used in combination with various electrically conductive ceramic plates as shown in the following Table 3, and induction heated to form discharge gap portions. Thus formed discharge gap portions theirselves, and those after the cooling and - 15 heating test, are tested on the same airtight sealness test as in Example l. The results are shown in the following Table 3. ~-- ~
: - 21-~`
:
.. .... , .. . . ~ .. .. ... .. . .. . ..
' ' ' ~ ~ "' ' ' ' ' . ' ' ` ' `
-- , ~: ' ' .
,::, .," '';,,, "".'' .:', ' ~' ~ ' .
:.'.. : ' : .'.. . ... '. ' - . .
3t7~1 1~ 1-` ~
. E~ 1: O O O O O O O O O X X x X
~u o o o o o o o o o o o o o ~ o o ~ ~ ~o ~ o I~ ~` r` o N I~ I~ 1~') e~ O ~ ~ .r ~ ~ ~ .. oD .r ~ v I ~
E~ .U~ ~ ,1 u~ ~ u~ u~ ,ol In U~ ~O Ul U7 U~ -' ~. ~, ~
¦ :~ ¦ N ~ N ¦ N ~ O ¦ U ¦ ~J ¦ e ~ ~
a~ _l ~ ___ ~ _ _ _ IZ I'~ 1~
~I ~I ~I ~I _l ~t ~I ~I ~ 1: ~ Ç
:~ ~ __ ~; ~: ~: ~a 1 33 ~ 78 ~
As seen clearly from the results of the above Table 3, the electrically conductive ceramic plates are substantially completely joined and sealed by means of inorganic glasses. However, the combinations of the OS plate of molybdenum silicide, tungsten carbide, or chromium oxide and the glasses of Reference 3-6, are insufficiently sealed, showing a leakage of He gas.
Example 3 In order to examine the state of the induction heating in the method of the present invention, the various inorganic glasses shown in the above Table l are disposed between the protrusions of the insulator bodies and metal plates or electrically conductive ceramic plates shown in the following Table 4 in the forms as 16 described in Table 4, and induction heated in conditions as described also in Table 4 to form discharge gap portions. Thus formed discharge gap portions theirselves, and those after the cooling and heating test, are tested on the same airtight sealness test as in Example l. The results are shown in the following Table 4.
~ ;' - : ; ~ - ~:: .,: :.
;...... . . . . .
. : . :::~ -; - . ~ - .
~ .
~ ~3 1 78 1 . ` .
I` ~- ~I;'r;~l 1;1 v v~ o o o o o o ~o o o O E~ _ O O O O O N ~ O N
1~: ~:: ~1 _~ ~1 _1 _1 ~1 ~__ ~1 O ' ~' JJ ~a- o o o o o o o o o o o ~ ~ P O O O O O O O O O O O
P: p _ ~1 ~1 ~1 ~1 ~ ~ ~1 ~ ~ ~1 ~/
_ _ O O OO O ..
h~ 1~~ ~
s~ ~(~ ~) ~ a) a~ a) ~ (~U~ ~11 ~ t~ o E~ ~ ~: ~a .~ ~a ~ ~ x ~ x ~ ~c ~ x ~ x ~ ~
H t~ ~ t~ ~a ~ ~a 111 1~ 1~
Ul U~ U~ Ul U~ ., = = C O u ~I = = = = ~3 = = = ..
OU ~ eS ~ ~ __ ~ ~ ~ m m a~
o = ~ ~3 ~ ~ ~. o u~. u~. o. ~. o o o o. ~o -~
IE~o=l~ 1~ l~olyl~T~o~
_ _ _ _ N N N N
'O~ ~ ~ ~ = ~= = = ~ ~ ~
___ _ ___ ___ ~ ~-1 ~,,",,,,,"- ~ ,.,,."", ,,,,",,`i~;, :-;. ~ . i .. ` . ~
AS seen from the results of Table 4, substan-tially completely joined and sealed discharge gap portions can be formed. However, in case where a stainless steel rod is not used and induction heating is 05 effected for a short time using powdery inorganic glass, the formed discharge gap portions show some leakage of He gas in the airtight sealness test after the cooling and heating.
Example 4 10The lightening arrestor insulators as shown in : Figs. la and lb are produced by preparing arrestor ZnO
element devices of Test Nos. 1-6 of the following Table 5 by using an inorganic glass and various sealing structures and structural conditions as shown in the ~ 16 following Table 5.
,;
` ~ ~20 ~ ' ~
~ i ~
:
317~1 6 ~ E 6 6 6 6 8 ~
O V U ~D CO IS7 N L'l ~0 _ 9 9 ~ 6 E 1~ L
a ~; 6 ~IZ 9 D 1 ~
I:o'V I.:DI I I 1~ ~
s= o ~ = a ,,, ~, v ~ ~ ~ ~ Q .~ ~ ~ ~
u~ t~ ~ R . ~iS u~ S v Z __ _ ~
E~ _l c~l ~ ~r In ~ ~V
~ __ O
~ 13317~1 AS seen from the above Table 5, various sealing covers and reinforcing members can be used, and environmental atmosphere around the ZnO element can be adjusted. These sealing covers and reinforcing members 05 can be sealed in a short time by high frequency induction heating of the electrically conductive sealing covers.
As apparent from the above foregoing explanations, the lightening arrestor insulator of the present invention has a discharge gap portion formed by directly joining a protrusion arranged in the inside of the insulator body and metal plates and/or electrically conductive ceramic plates having discharge electrodes by means of an inorganic glass, so that lightening arrestor 1~ insulators having a highly reliable airtightly sealed discharge gap portion can be obtained. As a result, accidental troubles in a power service line at a normal working voltage can be substantially eliminated, and damages caused by hygromeration can be noticeably decreased, so that electric power can be supplied with widely improved reliability.
Also, the lightening arrestor insulator of the present invention has electrodes and an arrestor ZnO
element~ device formed by directly joining the inside of the insulator body and metallic covers and/or electrically conductive covers acting as the electrodes ~ ~ ;
, - . .. .
13317~1 by means of an inorganic glass, so that lightening arrestor insulators having a highly reliable airtightly sealed arrestor ZnO element device can be obtained.
As a result, accidental troubles in a power service line 06 at a normal working voltage can be substantially eliminated, and damages caused by lightenings can be noticeably decreased, so that electric power can be supplied with widely improved reliability, from this aspect too.
According to the method of the present invention, the discharge gap portion is formed and sealed airtightly by partial heating of the lightening arrestor insulator by means of an induction heating, so that temperature rise of the whole insulator can be 16 avoided. As a result, an inner pressure within the discharge gap portion is not changed substantially after the airtight sealing, and lightening arrestor insulators of the desired properties can easily be obtained.
Also, according to the method of the present invention, the arrestor ZnO element device is formed and ~ sealed airtightly by partial heating of the lightening ; ~ arrestor insulator by means of an induction heating solely of the upper and lower electrically conductive -covers sandwiching the arrestor ZnO element via an 26 inorganic glass, so that a position of breakage of the ;~ insulator at the time of hit of a lightening can be ~ ~ .
~ - 28-: , ~ , .
~ ;, - ~ .
1 3 ~ ~ 7~ 1 restricted to the covers accommodating the arrestor ZnO
element. As a result, a crack formed in the covers can be prevented from developing to the insulator body, and discharge characteristic properties of the insulator at 06 the time of short-cut of an extraordinary excessive electric current can be improved.
In addition, a heating device in an apparatus for producing the lightening arrestor insulator can be minimized, and an environmental atmosphere around the arrestor ZnO element can be adjusted to desired ones.
Though the contacting end surfaces of the upper and lower covers and the insulator body are shown as tapered surfaces in the above embodiments, the contacting end surfaces may have another shapes, such as shown in Fig. 5.
The present invention is not limited to a suspension type lightening arrestor insulator, and clearly applicable to other shapes of lightening arrestor insulators.
Although the present invention has been explained with specific examples, it is of course àppa~rent to those skil}ed in the art that various changes and modifications thereof are possible without departing from the broad spirit and aspect of the present invention as defined in the appended claims.
~; :
Claims (7)
1. A lightening arrestor insulator having a discharge gap portion and an arrestor ZnO element device both built in a body of the insulator, comprising projected discharge electrodes arranged in the inside of the insulator body, the discharge gap portion being formed of a heat resistant protrusion arranged in the inside of the insulator body and surrounding the discharge electrodes, and a pair of metal plates and/or electrically conductive ceramic plates sandwiching the protrusion from both sides thereof and electrically connected to the discharge electrodes, and the pair of plates being joined and airtightly sealed to the protrusion via an inorganic glass.
2. A lightening arrestor insulator as defined in claim 1, wherein the protrusion being integrally formed with the insulator body.
3. A lightening arrestor insulator as defined in claim 1, further comprising a ceramic cylinder surrounding the projected electrodes between the pair of plates for firmly supporting the pair of plates.
4. A lightening arrestor insulator having electrodes and an arrestor ZnO element device both built in a body of the insulator, wherein, the arrestor ZnO
element device being formed of an arrestor ZnO element, the insulator body surrounding the arrestor ZnO element, and metallic covers and/or electrically conductive ceramic covers acting as the electrodes and sandwiching the arrestor ZnO element from both sides thereof, the covers being joined and airtightly sealed via an inorganic glass.
element device being formed of an arrestor ZnO element, the insulator body surrounding the arrestor ZnO element, and metallic covers and/or electrically conductive ceramic covers acting as the electrodes and sandwiching the arrestor ZnO element from both sides thereof, the covers being joined and airtightly sealed via an inorganic glass.
5. A lightening protective insulator as defined in claim 4, further comprising a reinforcing member around the arrestor ZnO element.
6. A method of producing a lightening arrestor insulator having an arrestor ZnO element device and a discharge gap portion both built in a body of the insulator, wherein a pair of metal plates and/or electrically conductive ceramic plates are electrically connected to projected discharge electrodes, disposed to sandwich and contact with a protrusion surrounding the discharge electrodes via an inorganic glass, and then heated by induction heating to melt the inorganic glass so as to join the pair of metal plate and/or electrically conductive ceramic plate and the protrusion by the molten glass, thereby to form an airtight sealing of the discharge gap portion.
7. A method of producing a lightening arrestor insulator having electrodes and an arrestor ZnO element device formed of an arrestor ZnO element and metallic covers and/or electrically conductive ceramic covers acting as the electrodes airtightly fixed and sealed in a cavity of the insulator body, wherein the covers are provided on the upper and bottom surfaces of the ZnO
element, mounted and pressed on the insulator body via an inorganic glass, and then heated and melted by induction heating so as to form an airtight fixing and sealing between the covers and the insulator body after solidification of the molten glass.
element, mounted and pressed on the insulator body via an inorganic glass, and then heated and melted by induction heating so as to form an airtight fixing and sealing between the covers and the insulator body after solidification of the molten glass.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63-67,311 | 1988-03-23 | ||
| JP63067311A JPH0752608B2 (en) | 1988-03-23 | 1988-03-23 | Lightning arrester and its manufacturing method |
| JP63144583A JPH01313815A (en) | 1988-06-14 | 1988-06-14 | Manufacture of lightening protection insulator |
| JP63-144,583 | 1988-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1331781C true CA1331781C (en) | 1994-08-30 |
Family
ID=26408502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000594425A Expired - Fee Related CA1331781C (en) | 1988-03-23 | 1989-03-22 | Lightening arrestor insulator and method of producing the same |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5012383A (en) |
| EP (2) | EP0334647B1 (en) |
| KR (1) | KR970004561B1 (en) |
| CN (1) | CN1037472C (en) |
| CA (1) | CA1331781C (en) |
| DE (2) | DE68908928T2 (en) |
| IN (1) | IN171826B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2687246B1 (en) * | 1992-02-07 | 1994-12-30 | Alsthom Gec | ZINC OXIDE SURGE PROTECTOR WITH SERIAL SPLITTER. |
| DE9321370U1 (en) * | 1992-09-28 | 1997-09-18 | Siemens Ag | Module for the discharge of electrical surges |
| US6612032B1 (en) * | 2000-01-31 | 2003-09-02 | Lexmark International, Inc. | Manufacturing method for ink jet pen |
| CN1331163C (en) * | 2004-05-26 | 2007-08-08 | 宁波电业局 | Composite protective cover insulator lightning arrester and producing method thereof |
| CN101354933B (en) * | 2008-09-23 | 2011-12-21 | 铜川供电局 | Internal electrode for composite insulator and equalizing ring configuring method as well as composite insulator thereof |
| EP2573885B1 (en) * | 2011-09-23 | 2016-08-10 | Epcos AG | Stacked Gas Filled Surge Arrester |
| CN102637524B (en) * | 2012-03-31 | 2014-08-06 | 国网浙江余姚市供电公司 | Power capacitor |
| CN102637490B (en) * | 2012-03-31 | 2014-03-19 | 乐清市风杰电子科技有限公司 | Improved porcelain binding post |
| CN102637523B (en) * | 2012-03-31 | 2014-08-27 | 国家电网公司 | Ceramic terminal for power capacitor |
| CN102637489A (en) * | 2012-03-31 | 2012-08-15 | 苏州贝腾特电子科技有限公司 | Improved ceramic binding post |
| CN104124011A (en) * | 2014-08-14 | 2014-10-29 | 陈晓光 | Integrated lightning arrester insulator |
| CN104394668B (en) * | 2014-11-23 | 2018-10-19 | 深圳市槟城电子有限公司 | A kind of component |
| CN110211783B (en) * | 2019-06-19 | 2021-10-22 | 江苏科瑞电气有限公司 | Test transformer |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH303804A (en) * | 1952-09-10 | 1954-12-15 | Oerlikon Maschf | Surge arresters. |
| US3727108A (en) * | 1972-02-15 | 1973-04-10 | Kearney National Inc | Surge arrester |
| DE2207009C3 (en) * | 1972-02-15 | 1979-03-22 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Surge arresters |
| US3715626A (en) * | 1972-03-01 | 1973-02-06 | Gen Electric | Spring plate contact and support for a lightning arrester sparkgap assembly and associated grading resistors |
| JPS5217719A (en) * | 1975-07-31 | 1977-02-09 | Matsushita Electric Ind Co Ltd | Recording method of video signal |
| JPS52114945A (en) * | 1976-03-23 | 1977-09-27 | Meidensha Electric Mfg Co Ltd | Arrester |
| FR2495827A1 (en) * | 1980-12-05 | 1982-06-11 | Tubes Lampes Elect Cie Indles | Gas filled lightning arrester - comprises closed ceramic chamber coated internally with thin glass film, and contg. electrodes |
| JPS57160555A (en) * | 1981-03-31 | 1982-10-02 | Sumitomo Light Metal Ind Ltd | Mold for casting used for purification of metal |
| DE3508030A1 (en) * | 1985-02-07 | 1986-08-07 | BBC Aktiengesellschaft Brown, Boveri & Cie., Baden, Aargau | Process for producing a surge arrestor using an active resistor core made from a voltage-dependent resistance material based on ZnO, and surge arrestor manufactured according to the process |
| JPS63136424A (en) * | 1986-11-27 | 1988-06-08 | 日本碍子株式会社 | Arresting insulator |
-
1989
- 1989-03-21 IN IN227/CAL/89A patent/IN171826B/en unknown
- 1989-03-22 DE DE89302884T patent/DE68908928T2/en not_active Expired - Lifetime
- 1989-03-22 CA CA000594425A patent/CA1331781C/en not_active Expired - Fee Related
- 1989-03-22 DE DE68922909T patent/DE68922909T2/en not_active Expired - Fee Related
- 1989-03-22 EP EP89302884A patent/EP0334647B1/en not_active Expired - Lifetime
- 1989-03-22 EP EP92114053A patent/EP0518386B1/en not_active Expired - Lifetime
- 1989-03-23 CN CN89102584A patent/CN1037472C/en not_active Expired - Fee Related
- 1989-03-23 KR KR1019890003680A patent/KR970004561B1/en not_active IP Right Cessation
-
1990
- 1990-07-27 US US07/561,234 patent/US5012383A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0518386A3 (en) | 1993-11-10 |
| DE68908928T2 (en) | 1994-03-17 |
| CN1037472C (en) | 1998-02-18 |
| EP0334647A1 (en) | 1989-09-27 |
| KR890015295A (en) | 1989-10-28 |
| EP0518386B1 (en) | 1995-05-31 |
| EP0334647B1 (en) | 1993-09-08 |
| KR970004561B1 (en) | 1997-03-29 |
| DE68908928D1 (en) | 1993-10-14 |
| CN1040108A (en) | 1990-02-28 |
| US5012383A (en) | 1991-04-30 |
| IN171826B (en) | 1993-01-23 |
| DE68922909T2 (en) | 1995-12-07 |
| EP0518386A2 (en) | 1992-12-16 |
| DE68922909D1 (en) | 1995-07-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |